1. Technical Field
The present invention relates to a disk drive apparatus used as a data recording means in a computer and, in particular, to a disk drive apparatus that can increase speed when a magnetic head seeks a track of interest.
2. Description of the Related Art
Hard disk drives are commonly used as data recording means in a computer having a structure with one or more coaxial magnetic disks that are driven by a spindle motor. A magnetic head faces the magnetic disks to read and write data, and this magnetic head is driven by an actuator, generally speaking, a Voice Coil Motor. The magnetic disk, magnetic head, and actuator are contained in an enclosure called an enclosure case. A major technical task in the field of hard disk drives is to increase storage capacity per sheet of magnetic disk and to increase the speed of reading data from and writing data into the magnetic disk.
The performance of a voice coil motor is enhanced by thickening a permanent magnet constituting the voice coil motor, but there is a limit presently. Then, the present inventor et al. paid attention to the increase of driving speed by enlarging the torque generated in a voice coil through elongating the distance between a rotation center of the voice coil and an end portion of the voice coil. FIG. 3 shows an actuator 26 including a voice coil 32. In order to elongate the distance between the rotation center and end portion of the voice coil 32 (hereinafter, L), it is necessary to ensure a space for the purpose in the enclosure case.
Nevertheless, it is not easy in a current Hard Disk Drive to secure such a space in the enclosure case. This is because parts such as the magnetic disk, and Voice Coil Motor are arranged in the enclosure case in high density. In a conventional Hard Disk Drive, a magnetic disk is arranged so that a center of the magnetic disk coincides with a center of the enclosure case in the direction of width.
Against this, in the present invention, a magnetic disk is arranged so that a center of the magnetic disk is shifted from a center of the enclosure case in the direction of width. Therefore, the space for elongating the distance L is secured by enlarging an area of any one of left and right spaces in the enclosure case with making the center of the disk-like recording medium as a boundary.
Thus the present invention is a disk drive apparatus, comprising: a disk-like recording medium that can be randomly accessed; a magnetic head to record or reproduce a signal, the magnetic head being provided opposite to the disk-like recording medium; an actuator to seek the magnetic head above the disk-like recording medium; and an enclosure to contain the disk-like recording medium, the magnetic head, and the actuator, the enclosure being configured so that one area to contain the disk-like recording medium is larger than another area to contain the disk-like recording medium, the areas being set on a center line of the disk-like recording medium as a boundary in the direction of width.
In the present invention, it is effective to make dimensions of the disk-like recording medium smaller than those of a disk-like recording medium corresponding to a form factor of the enclosure. Thus, by reducing a diameter of the disk-like recording medium, it becomes possible to shift the disk-like recording medium from the enclosure. In addition, as is well known, the form factor denotes the width of an enclosure, that is, an enclosure case, constituting a Hard Disk Drive. Usually, if the form factor is 3.5 inches, a disk-like recording medium having the diameter of 3.5 inches (generally, 95 mm) corresponds to this.
Nevertheless, in the present invention, a disk-like recording medium having the diameter smaller than this is mounted. This means that the dimensions of the disk-like recording medium is smaller than those of the disk-like recording medium corresponding to the form factor of the enclosure. In addition, in case it is expressed that the diameter of a magnetic disk is reduced, this expression means this.
Furthermore, in the present invention, it is possible to diagonally arrange the disk-like recording medium and actuator in the enclosure and arrange the actuator in the side having the larger accommodation area. Owing to such arrangement, it becomes possible to enlarge the dimensions of the actuator, more concretely, to elongate the distance L of the Voice Coil Motor. Therefore, the performance of the actuator is enhanced, and hence it is possible to increase the seek speed of the magnetic head.
In addition, the meaning of the fact that the actuator is arranged in the side having the larger accommodation area is not that the entire actuator exists in the side having the larger accommodation area, but that, at least, a drive shaft of the actuator is positioned in the side having the larger accommodation area.
In addition, the present invention provides a Hard Disk Drive, comprising: a magnetic disk to record data thereon; a head to read or write data from or to the magnetic disk; a Voice Coil Motor to drive the head; and an enclosure case to contain the magnetic disk, the head, and the Voice Coil Motor, the enclosure case having a 3.5 inch form factor, and the magnetic disk being arranged so that a center of the magnetic disk is arranged to be shifted from a center of the enclosure case in the direction of width, and an outer diameter of the magnetic disk being 84xc2x10.1 mm (millimeter).
In this disk drive apparatus, the form factor of the enclosure case is 3.5 inches, but the outer diameter of the magnetic disk is 84xc2x10.1 mm. Thus, although the outer diameter of the 3.5 inch magnetic disk is 95 mm, this disk drive apparatus includes the magnetic disk having the diameter smaller by 11 mm than that of the 3.5 inch magnetic disk. Therefore, owing to the use of this magnetic disk, it is possible to generate a space for elongating the distance L of the Voice Coil Motor by arranging the magnetic disk with shifting the center of the magnetic disk from the center of the enclosure case in the direction of width. In addition, since the diameter of the magnetic disk is reduced to 84xc2x10.1 mm, it is possible to suppress the fluttering of the magnetic disk that is smaller than that of the 3.5 inch magnetic disk, even if the magnetic disk is rotated at the high rotation speed of, for example, 10,000 rpm.
Furthermore, it is possible to decrease the power consumption. Therefore, in the present invention it has critical meaning for increasing the seek speed and reducing the fluttering and power consumption to make the magnetic disk in 84xc2x10.1 mm diameter. Moreover, although, here, the 84 mm magnetic disk is exemplified, it goes without saying that it is allowed in the present invention to use a magnetic disk having the diameter smaller than this dimension.
In the present invention, it is possible to make the distance L between the rotation center of the Voice Coil Motor and the end portion of the voice coil at 34 to 37 mm. The larger this distance L is, the faster the driving speed of the Voice Coil Motor, that is, the seek speed of the magnetic head can be made. Nevertheless, as there is a limit of a space allowable in the enclosure case, the distance of 34 to 37 mm is positioned as the distance necessary for getting the seek speed highest in the range allowable in the enclosure case.
In the present invention, it is desirable to make the shift between the center of the magnetic disk and the center of the enclosure case in the direction of width, that is, eccentricity 1 to 5.5 mm. This is because it is impossible to sufficiently elongate the distance L at the eccentricity less than 1 mm, and on the other hand, it is impossible to keep sufficient rigidity due to thin side walls of the enclosure case at the eccentricity more than 5.5 mm. Hence the desirable eccentricity is 3 to 4 mm. In addition, in the present invention, by reducing the diameter of the magnetic disk, the magnetic disk becomes eccentric in the direction of the width of the enclosure case, that is, is shifted in any one of left and right sides. Nevertheless, in the present invention, this is not limited in the cross direction, but it is possible to be shifted in the longitudinal (depth) direction of the enclosure case.
In addition, the disk drive apparatus according to the present invention can realize not only the high-speed read/write with adapting to the disk drive apparatus having the high rotation speed such as 7,200 rpm, 10,000 rpm, or 12,000 rpm, but also the reduction of the fluttering and power consumption of the magnetic disk.
In a Hard Disk Drive, a magnetic disk and a Voice Coil Motor occupy a large rate in weight. It is desirable that the center of gravity of the Hard Disk Drive coincides with a center of the enclosure case. The present invention has such an effect that it is possible to make the center of gravity of the Hard Disk Drive get closer to the center of the enclosure case by eccentrically locating the magnetic disk, and locating the magnetic disk and Voice Coil Motor on a diagonal line of the enclosure case as much as possible. Therefore, the present invention provides a Hard Disk Drive, comprising: a magnetic disk to record data thereon; a head to read or write data from or to the magnetic disk; a Voice Coil Motor to drive the head; and an enclosure case to contain the magnetic disk, the head, and the Voice Coil Motor, wherein: the magnetic disk is arranged in an area of the enclosure case so that one area to contain the magnetic disk is larger than another area to contain the magnetic disk, the areas being set on a center line of the magnetic disk as a boundary in the direction of width; the magnetic disk and the Voice Coil Motor are arranged on a diagonal line of the enclosure case; and thereby a center of gravity of the Hard Disk Drive conforms to a center of a surface of the enclosure case or gets closer to the center of the surface of the enclosure case.
In the present invention, in order to make an accommodation area of any one of left and right spaces larger than that of another space with the center of the magnetic disk as a boundary, it is good enough to reduce the diameter of the magnetic disk. Thus, it is good enough to make the dimensions of the magnetic disk smaller than those of a magnetic disk corresponding to a form factor of the enclosure case.
Problems to be Solved by the Invention
As for the latter, it is possible to increase the speed of reading data from and writing data into the magnetic disk by reducing the seek time of a magnetic head moving to a track of interest on the magnetic disk. It is possible to increase the seek speed of the magnetic head by enhancing the performance of a Voice Coil Motor since the magnetic head is driven by the Voice Coil Motor as described above. In order to enhance the performance of the Voice Coil Motor, it is sufficient only to change a permanent magnet, which constitutes the voice coil, to another magnet that has stronger magnetic property or to increase a magnetic field applied to the Voice Coil Motor by thickening the permanent magnet. Nevertheless, up to now, a permanent magnet having magnetic property exceeding that of the permanent magnet used in the Voice Coil Motor has not been found. In addition, there is a limit of thickening the permanent magnet in a Hard Disk Drive requested to be small-sized.
In addition, it is possible to increase the data read/write speed by accelerating the rotation speed of the magnetic disk. Therefore, 7,200-rpm, 10,000-rpm, and 12,000-rpm high-speed Hard Disk Drives have been cast in market. Nevertheless, the high-speed rotation of the magnetic disk increases not only fluttering of the magnetic disk, but also power consumption. The increase of the fluttering badly affects the accuracy of data read/write.
Then, a task of the present invention is to provide a disk drive apparatus that can increase the seek speed of a magnetic head. Furthermore, another task of the present invention is to provide a disk drive apparatus that not only can increase the seek speed of a magnetic head but also can suppress the increase of fluttering and power consumption at high rotation speed.
Advantages of the Invention
As described above, according to the present invention, it is possible to increase the average seek time, and hence it is possible to accelerate data read/write speed. Furthermore, according to the present invention, it is possible to realize the reduction of the fluttering and power consumption of a magnetic disk. Moreover, the present invention has such an effect that it is possible to make the center of gravity coincide with or get closer to a center of an enclosure case and to make writing of servo tracks easy.